Electric circuit breaker of bushing type



G. YABUNo ETAL. 2,562,160

CIRCUIT BREAKER OF BUSHING TYPE 2 Sheets-Sheet l July 24, 1951 ELECTRI C F1' led July 9, 1949 G. YABUN ET AL ELECTRIC CIRCUIT BREAKER oF BUSHING TYPE July 24, 1951 2 Sheets-Sheet 2 Filed July 9, 1949 m f. m p, .N ig mww n v/ M HM le f MMMW mfwmw/ HHH n@ GHSMTWM fw A w fb Patented July 24, 1951 ELECTRIC CIRCUIT BREAKER, OF BUSHING TYPE Gaiseki Yabuno and Hajime Maki, Hitachi, Shintaro Ajima, Ishikawa, NakaeGun, and Masatoshi Kuwayama and Takuro Ando, Taga- Town, Taga-Gun, Japan, assignors to Hitachi Limited, Tokyo, Japan, a Japanese corporation Application July 9,1949, Serial No. 103,902

2 Claims.

This invention relates to improvements in bushing type electric circuit breakers, and more particularly to a special construction and arrangement of arc suppressing means and movable electrode of a bushing type electric circuit breaker, and has for its object to provide improved circuit interrupting characteristics by increasing the arc extinguishing effect.

In the accompanying drawing forming a part of this specication:

Figure 1 isY a sectional elevation of a bushing type circuit breaker as an embodiment of this invention showing the movable electrode in open position,

Figure 2 is a sectional elevation of the arc suppressing chamber and a part of movable electrode'in an enlarged scale for showing its detailed constructionV and for explanation of arc extinguishing action,

Figure 3 is a cross-sectional view taken on the line A`A of Fig. 2, and

Figure 4 is a similar cross-sectional View taken on the line B-B of Fig. 2.

Now referring to Fig. 1 of the drawing, which represents a construction of bushing type circuit breaker embodying this invention, I designates supporting insulators having a metallic base 2 secured thereto. 3 is a porcelain bushing secured to the base 2 to form an oil tank. 4 designates a metallic casing fixed on ther top of bushing 3 having a top cover 5. 6 shows a bottom plate securedto the base 2, thus the parts including I to 6 constitute outer shells of the'circuit' breaker. 1 designates an insulator cylinder for protecting the bushing 3 of oil reservoir from the internal pressure generated when the circuit breaker is opened. The cylinder 1 is secured toand suspended from the top casing by means of metallic hanger 8., 9 represents an oil level gauge. I0 designates an insulator cylinder forming arc` suppressing' chambers therein, which is secured onto bottom parts |I and I2 of the cylinder 1. I3 isa stationary electrode arranged in the arc sup- 'pressingl cylinder III, having a downwardly projecting conducting rod I4. I5 is a fixed contact member and I6 is a terminal conductor. I1 designates a circuit interrupting chamber arranged above the arc suppressing chamber separated with oil gap and I8 shows upper contact piecesy of annular shape'.

I9 is a hollow movable electrode which is connected at its upper end to the top of swinging link 2I|1which has a roller at its lower end. The roller2|A engages in guide groove 22 provided in the metallic casing 4. 23 is a bell crank lever pivoted to an axis 24 which is tted to the supporting frame 25 fixed on legs 26. 21 represents metallic members for suspending the circuit interrupting chamber I1 from the frame 25. 28 is a horizontal link connecting the bell crank lever 23 to a crank arm 29 which is fixed to the shaft to be turned thereby. The shaft 30 is xed to an insulating bushing 3| which insulates the shaft from the earth and is turned by compressed air motor or other suitable prime mover on the ground, thereby turning the crank 29 to move the link 28, bell crank 23, and swing link 20, which latter is moved along the guide groove 22 by means of roller 2| so that the hollow movable electrode I9 is moved in Straight vertical directions to make contact with or to be separated from the lower stationary electrode I3 arranged in arc suppressing chamber I0. The mechanism consisting of link 20, guide groove 22 and bell crank lever 23 for operating movable electrode I9 in straight vertical directions is known as a straight line motion mechanism. 32 is a spring for accelerating'the circuit opening motion of the movable electrode. In the hollow movable electrode is provided a piston 33 put on piston rod 34, the upper end of which is xed to the frame 35 which projects upwardly from the supporting frame 25. 3B represents a gas relief and 31 is its cover. 38 is an upper terminal conductor which is connected to an electric circuit together with the lower terminal conductor I6. In the above We have brieiiy explained a construction and operation of the bushing type electric circuit breaker.

Next referring to Figs. 2 to 4, the main feature of this invention will be explained more in detail. The cylindrical shell forming arc suppressing chambers therein is made of insulating material such as phenol resin or resinous compound and has arranged therein arc suppressing elements |0I, |02, |03, |04, |05 etc. made of phenol resin or other resinous compound and the like material in spaced relation, which are clamped together by bolts |06 in the cylinder I0. These arc suppressing elements are provided with central openings |01 for passing the movable electrode therethrough and a horse shoe magnet |08 located in the oil space above the stationary electrode and biased to one side oi the opening so as to form oil chamber |09 between two legs of the magnet. Above the magnet I 03, an intermediate electrode ||I'.| is provided on one side of the central opening and oil blow-out opening is formed above the intermediate electrode. The magnet, oil chamber, intermediate electrode and oil blow-out hole are biased on one side of the opening |01. Oil circulating spaces g are provided on both sides of these arc suppressing elements, thereby communicating the upper and lower oil spaces H3 and H2 of the arc suppressing chamber so as to equalize oil pressure.

rThe metal disk H4 having the stationary contact I3 iixed thereto is provided with pressure relief holes H5 which are normally covered by a disc valve H6 having springs H1 and when an abnormal pressure occurs in the arc suppressing chamber in case of opening circuit the disc valve IIB is opened against the spring force to relieve excess pressure out of the arc suppressing chamber through relief holes H5 and trodes is increased. According to this invention L the initial arc or primary arc A1 is forced to curve by means of the magnet |08 in the oil chamber |09, thereby promoting generation of vapour of dissociation caused by the contact of oil and electric arc in the oil chamber |09 so that the pres- 1 sure of oil in chambers |09 and H2 is increased, Such arc biasing phenomena are called the arc controlling action in this speciiication. When the tip of movable electrode I9 is moved upwards passing over the intermediate electrode H0, then the arc is divided into two portions i. e., the primary arc A1 (between stationary electrode and intermediate electrode) and the secondary arc A2 (between intermediate electrode and movable eletrode). The secondary arc A2 is driven towards the blow-out opening III by the intermediate electrode H0 and is blown out through the opening `by the generated gas pressure and oil current occurring in the oil duct so that the arc can be suppressed. Moreover according to the present invention the surface of arcing electrode ||0 is swept and cooled by oil current as shown by the arrow in Fig. 2. On the other hand, the oil pressure from the chamber H2 acting on the chamber H3 through the oil space y forces the cool oil in the chamber H3 to flow through the opening |01 in the direction opposite to the moving direction of the movable electrode I9 as shown by the arrow when the electrode is moving to open the guide opening |01. washes the tip of moving electrode I9 and acts on the secondary arc A2 to drive it towards the oil blow hole I I.

Although the above described washing action of electrode by the oil current and the blowing action against the secondary arc A2 in the blow-out opening will result in a sufficient arc extinguishing effect for quickly suppressing the arc, according to this invention in addition to it the movable electrode I9 is made hollow and a stationary piston 33 is provided therein. The piston operates to eject oil contained in the hollow part of the movable electrode I9 into guide opening |01 as shown by the arrow in Fig. 2 through oil holes H9 provided in the tip of the movable electrode by the piston action occurring when the electrode is moved to open the circuit. This oil jet rushes into the oil vapour generated by the dissociation due to the primary arc A1 to cool it down and accelerate its de-ionzation and also the oil jet This oil current rushes in the primary arc A1 to maintain dissociation of oil for positively generating necessary arc suppressing pressure.

Since the oil jet continues during the circuit opening motion of electrode I9, it is eiective to extinguish even a trace of arc at an instant of zero current during the change of arc current which occurs in the form of sine wave, thereby improving the recovery of die-electric strength between electrodes in the arc suppressing chamber and preventing arc-back.

As above described, according to this invention excellent arc-extinguishing effect is resulted and the circuit interrupting ability of circuit breaker is remarkably improved by the combined action of the arc controlling action of magnet for the struck arc, the arc splitting action by the intermediate electrode, sweeping and blowing action by oil current and the arc blowing-off action of the central oil jet ejected from the tip of hollow movable electrode.

In the foregoing, we have described an embodiment of our invention referring to the drawings wherein the arc suppressing chamber I0 is arranged in the bottom of insulator cylinder 'I, and the movable electrode I9 and its operating mechanism are arranged above the arc suppressing chamber so that the movable electrode is moved upwardly in case of opening the closed circuit. But the total device shown in Fig. 1 can be arranged upside down, i. e., the arc suppressing chamber I0 can be fixed to the upper part in the inside of the inverted protective insulator cylinder 'I and the movable electrode operating mechanism can be arranged in the metallic casing xed to the ybottom of insulator bushing 3 by providing suitable oil tight seals so that the movable electrode can be moved downwardly for opening the closed contact.

It should be understood that various modications may be resorted to within the scope of the appended claims without departing from the spirit or sacrificing any of `the advantages of the invention.

Having thus described our invention, what we claim as new and desire to secure 'by Letters Patent of the United States is:

l. In a bushing type electric circuit interrupter, 1n combination a container for oil, an arc suppressing cylinder mounted in said container and having an aperture formed centrally in one end thereof, three insulating discs disposed in axially `spaced relationship in said arc suppressing cylinder and spaced from the opposite ends of the latter. said insulating discs being formed with central openings registering axially with said aperture in said cylinder, the space between said one end of the cylinder and the adjacent one of said insulating discs and the space between the other end of said cylinder and the one of Said discs adjacent thereto constituting upper and lower oil chambers, respectively, a xed electrode mounted in said lower oil chamber, an elongated movable electrode mounted for axial movement through said aperture and said openings into and out of engagement with said fixed electrode, a pressure by-pass passage denned 'between the inner wall surface of said arc suppressing cylinder and peripheral portions of said insulating discs for communicating said lower oil chamber with said upper oil chamber, a magnet mounted at one side of the space between the central one of said insulating discs and said disc adjacent said otheri end of the cylinder to laterally deflect the are` formed between said movable and fixed electrodos aseaieo when the latter are separated, an intermediate electrode carried lby said central insulating disc at said one side of said opening therein for splitting the arc into a primary arc in said space containing said magnet and a secondary are in an arc extinguishing space defined between said central insulating disc and said disc adjacent said one end of the cylinder, said magnet operating to increase the eiective length of the primary arc for promoting the more rapid decomposition of the oil in contact therewith so that a substantial pressure increase is obtained in said magnet containing space, and `a port formed in the side of said arc suppressing cylinder opening into said arc extinguishing space, the pressure increase in said magnet containing space being effective to produce an oil flow into said arc extinguishing space through said opening in the central disc in the direction of circuit interrupting movement of said movable electrode and being communicated to said upper oil chamber through said lower oil chamber and said by-pass passage to effect an oil flow from said upper oil chamber past the contact end of said movable electrode and into said arc extinguishing space in the direction opposite to the circuit interrupting movement of said movable electrode so that the oil ows into said arc REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,084,936 Bresson June 22, 1937 2,112,033 Lingal Mar. 22, 1938 2,227,134 Hara Dec. 31, 1940 

